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Charley horse


A charley horse is the common name for a muscle spasm or cramp. Muscle spasms can occur in any muscle in the body, but often happen in the leg. When a muscle is in spasm, it contracts without your control and does not relax.

Alternative Names:

Muscle spasm


Muscle spasms often occur when a muscle is overused or injured. Things that might bring on a muscle spasm include:

  • Exercising when you have not had enough fluids (you're dehydrated).
  • Having low levels of minerals such as potassium or calcium.

Some spasms occur because the nerve that connects to a muscle is irritated. One example is when a herniated disk irritates the spinal nerves and causes pain and spasm in the back muscles.

Spasms in the calf often occur while kicking during swimming or running. They can also happen at night when you are in bed. Upper leg spasms are more common with running or jumping activities. Spasm in the neck (cervical spine) can be a sign of stress.


When a muscle goes into spasm it feels very tight. It is sometimes described as a knot. The pain can be severe.

Exams and Tests:

To diagnose a spasm, your health care provider will look for tight or hard muscles that are very tender to the touch. There are no imaging studies or blood tests for this condition. If the spasm is caused by nerve irritation, such as in the back, an MRI may be helpful to find the cause of the problem.


Stop your activity and try stretching and massaging the affected muscle at the first sign of a spasm. 

Heat will relax the muscle at first. Ice may be helpful after the first spasm and when the pain has improved.

If the muscle is still sore after heat and ice, you can use nonsteroidal anti-inflammatory medicines to help with pain. In more severe cases, your health care provider can prescribe antispasm medicines.

After you get treated, your provider should look for the cause of the spasm so that it doesn't happen again. If an irritated nerve is involved, you might need physical therapy or even surgery.

Drinking water or sports drinks when exercising can help ease cramps due to dehydration. If drinking water alone is not enough, salt tablets or sports drinks may help replace minerals in your body.  

Outlook (Prognosis):

Muscle spasms will get better with rest and time. The outlook is excellent for most people. Learning how to exercise properly with the right training and enough fluid intake can prevent spasms from occurring regularly.

You might need other treatments if an irritated nerve caused the spasm. Results from these treatments can vary.

When to Contact a Medical Professional:

Call your provider if:

  • You have a muscle spasm with severe pain.
  • You have weakness with your muscle spasm.
  • You have a muscle spasm that does not stop and it spreads to other parts of the body.

Even if your spasms are not severe, your provider can help you change your exercise program to reduce the risk of spasms in the future.


Things you can do to lessen the chance of muscle cramps include:

  • Stretch to improve your flexibility.
  • Change your workouts so that you are exercising within your ability.
  • Drink plenty of fluids while exercising and increase your potassium intake. Orange juice and bananas are great sources of potassium.


Geiderman JM, Katz D. General principles of orthopedic injuries. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier Mosby; 2014:chap 49.

Nakamura N, Rodeo SA, Alini M, Maher S, et al. Physiology and pathophysiology of musculoskeletal tissues. In: Miller MD, Thompson SR, eds. DeLee and Drez's Orthopaedic Sports Medicine. 4th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 1.

Review Date: 5/9/2015
Reviewed By: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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